What is a Subnet Mask?

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What is a Subnet Mask?

Post by EchoLynx » Mon Aug 25, 2008 7:39 pm

I have recently acquired a FreeNAS box for my backups but am puzzled by the fields asking for a subnet mask- I know it's - but what does that mean and what does it have to do with me accessing my data?

Saturday August 9th, 2008: Acquired Technician-class Amateur Radio License. Assigned call KB3ROH.
February (?) 2010: Acquired General-class Amateur Radio License.

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Re: What is a Subnet Mask?

Post by msuggs » Tue Aug 26, 2008 4:04 am

The subnet mask helps to identify which parts of an IP address belong to the network ID and which part is the host ID. For example, with an address of, and a subnet mask of, the Network ID is 200.200.200, and the Host ID is 5.

Basically without it your IP address means nothing unless the subnet mask is there to help other machines decipher and communicate with it.

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